Miniaturization of semiconductor devices of recent years is making progresses, and scanning electron microscopes (hereinafter abbreviated to SEMs), scanning transmission electron microscopes (hereinafter abbreviated to STEMs), transmission electron microscopes (hereinafter abbreviated to TEMs), and so on are used for analyses of defective portions in manufacturing steps. In order to observe a sample using a STEM or a TEM from among these, it is necessary that a portion of an object to be analyzed be cut out from a sample such as a semiconductor wafer or a semiconductor chip and be machined so thin that an electron beam can penetrate. A focused ion beam (hereinafter abbreviated to FIB) apparatus is used in this application. With the FIB a situation of machining can be observed by detecting and imaging a secondary signal such as secondary electrons generated from the sample by irradiating the sample with an ion beam; however, since the resolution is low and it is impossible to cope with recent miniaturization of subject samples, an apparatus equipped with both of an FIB column and an SEM column for a single sample chamber has been developed. This apparatus is hereinafter referred to as an FIB-SEM. Furthermore, in order to observe a sample of a thin leaf machined by an FIB apparatus using an STEM, an apparatus equipped with both of an FIB column and an STEM column has been developed. This apparatus is hereinafter referred to as an FIB-STEM.
In the above-described FIB-SEM and FIB-STEM, because their respective columns occupy large volumes, it is impossible to make their optical axes coaxial with each other. Accordingly, contrivances are made to place the sample at a position and an orientation appropriate relative to the respective optical axes. For example, a high-resolution image can be obtained by rotating the sample such that the machined surface of the sample is placed perpendicular to the optical axis of the SEM (for example, see Patent Literature 1).